Knuth is considered a famous programmer, known for his geek humor: as examples, he pays a finder's fee of $2.56 for any typos/mistakes discovered in his books because "256 pennies is one hexadecimal dollar". (His bounty for errata in 3:16 Bible Texts Illuminated, is, however, $3.16). Version numbers of his TEX software approach pi, that is versions increment in the style 3, 3.1, 3.14 and so on, version numbers of Metafont approach E similarly; he once warned users of his software, "Beware of bugs in the above code; I have only proved it correct, not tried it." (source)

Knuth is the author of 3:16 Bible Texts Illuminated (1991), ISBN 0895792524, in which he attempts to examine the Bible by a process of "stratified random sampling," namely an analysis of chapter 3, verse 16 of each book. Each verse is accompanied by a rendering in calligraphic art, contributed by a group of calligraphers under the leadership of Herman Zapf.

Knuth's hobbies include music, and specifically playing the organ. He has a pipe organ installed in his home. Knuth disclaims any particular talent in the instrument, however. He does not use email, saying that he used it from about 1975 until January 1, 1990, and that was enough for one lifetime. He finds it more efficient to respond to correspondence in "batch mode", such as one day every three months, to be sent by snail mail.

He is married to Jill Knuth, who published a book on liturgy. They have two children.

Knuth published his first "scientific" article in a school magazine in 1957 under the title "Potrzebie System of Weights and Measures," part of which included defining the fundamental unit of length as the thickness of MAD magazine #26, and naming the fundamental unit of force "whatmeworry". MAD magazine bought the article and published it in the June 1957 issue.